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Old Oct 13, 2012, 04:09 AM
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jgalexander's Avatar
United States, CA, Calabasas
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That's for a 3s batt. If you want to look at 4s numbers, you have to change the "# serial" box (it's in the battery row) from "3" to "4". Take a look at amps, watts, flight times, static thrust, and pitch speed.
J
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Old Oct 14, 2012, 10:44 AM
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Rem Fodder's Avatar
Canada, ON, Port Hope
Joined Apr 2012
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Hey there Josh, I noted in an earlier post you mentioned that you were using a tandem pack setup ( 2 x 2200 mah) in your model. I'm curious, what would the advantage be to doing that vs. a single 4s 4400? I am assuming that the packs are series connected?

Rem
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Old Oct 14, 2012, 01:26 PM
Flying Full Size & Fun Size :)
jgalexander's Avatar
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Hi Rem,
There were three benefits for me.
1. More mAh = more flight time. With that huge wing on there, the beaver didn't seem to mind the extra weight at all.
2. I can fit 2200's in there (barely). I *think* fitting a 4000+ mAh batt in there would be impossible.
3. Using the 2200's gives me the flexibility to use the same packs in a bunch of different planes. I use a single 2200 in my smaller birds, and put two in parallel in bigger planes. Basically, I don't have to buy as many batteries.
So far it's worked very well for me.
J
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Old Oct 15, 2012, 02:56 PM
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So you are running at 7.4 volts? Now that does surprise me! Forgive my ignorance, but I never imagined running a motor like the P32 on those voltages. I was always under the impression from basic ohm's law that lower voltages meant higher current draws? Not trying to stir up a debate on the issue, just trying to learn, as I have found so far since coming back to the hobby that the learning curve is steep! What kind of flight times are you getting? The 4 cell 3200 mah packs I use give a pretty honest 12 minutes of flight time with plenty of juice left for botched landings. Mind you though, I tend to fly conservatively and minimize aerobatics.

Rem
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Old Oct 15, 2012, 03:09 PM
Flying Full Size & Fun Size :)
jgalexander's Avatar
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Hey Rem, 14.8v baby! No 2s over here
I run 2 x 4s 2200 with my two-blade 13x6.5 prop, and 2 x 3s 2200 with my three-blade 12x8x3 prop. Running either setup in parallel gives me 4400mah, which means nice, long 14 or 15 min flights.
Josh
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Old Oct 15, 2012, 03:39 PM
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how do u do parallel
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Old Oct 15, 2012, 03:44 PM
Flying Full Size & Fun Size :)
jgalexander's Avatar
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Quote:
Originally Posted by hobbiconexstar View Post
how do u do parallel
Like this: http://www.google.com/search?q=lipo+...iw=320&bih=416
-J
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Old Oct 16, 2012, 11:06 AM
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Rem Fodder's Avatar
Canada, ON, Port Hope
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Josh, I think that was a brain fart I had. For some reason I had the notion of 2200 2s packs, don't ask why..........been sucking up too many neutrons at work lately! Your setup makes total sense now. Thanks.

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Old Oct 16, 2012, 03:35 PM
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Quote:
Originally Posted by jgalexander View Post
Well, it really depends on the setup. A 12x8x3 on 3s only draws 38A. Doesn't seem like a big risk to me. Conversely, a 13x6.5 on 4s draws 52A - a little more iffy.
Josh
We're !00% in agreement....

For a newbie, all the calculations may put him/her away from electric for ever. At the early stage of electric, a lot to take in but once you get your head around all this calc then it becomes "Electric for ever"

Cheers
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Old Oct 16, 2012, 05:08 PM
Flying Full Size & Fun Size :)
jgalexander's Avatar
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Quote:
Originally Posted by CurrentDude View Post
We're !00% in agreement....

For a newbie, all the calculations may put him/her away from electric for ever. At the early stage of electric, a lot to take in but once you get your head around all this calc then it becomes "Electric for ever"

Cheers
Agreed - it is a bit to learn. On the flip side though, it's just like anything else. When I started out I made some mistakes, read a lot, asked a few questions, let Google be my friend (most questions have already been answered - you just gotta fine the answers), and then found tools I could use to figure stuff out on my own (most of the time ).
That eCalc is great (http://www.castlecreations.com/suppo...alculator.html).
Progressive RC has a ton of data on motors, esc's, and batts (http://www.progressiverc.com/research).
There's a thread on here with IR readings of lots of common batts (http://www.rcgroups.com/forums/showthread.php?t=1578001).
Happy flyin y'all,
J
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Old Oct 29, 2012, 09:28 PM
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United States, FL, Orlando
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can someone that happens to have thier cowl off tell me this distance from the firewall to the back of the prop. (face of the adapter) Im using another brand motor etc would help me fit cowl etc. I know I can just fit it to the cowl but it would help to have a measurement also. Thanks!
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Old Oct 30, 2012, 08:59 AM
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United States, ME, Bangor
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Josh,
Would a 4s 1000 mah lipo work on 50amp esc?
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Old Oct 30, 2012, 09:06 AM
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United States, ME, Bangor
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Josh,
Would a 4s1000mah work on the 50 amp esc?
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Old Oct 30, 2012, 01:27 PM
Flying Full Size & Fun Size :)
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Probably, but if you're considering using a 4s 1000mah batt for the beaver, that wouldn't be the way to go.

Electric power systems aren't rocket science, but to put together a good setup you do need to consider the prop, motor, esc, and batt as a unit. It's a bit different from glow/nitro, where it's mostly just the engine and prop.

In short, here's what you need to consider.
1. The motor and prop need to produce enough thrust and pitch speed to suit the flying you want to do.
2. The amp and watt draw of the motor/prop should be about 15-20% less than the maximum limits of the ESC.
3. The battery should be able to comfortably supply the current required by the motor/prop. For example, my batteries for my 3s 4400mah setup are 20C. That means they can supply 20*4.4=88 amps of current without breaking a sweat (or puffing, exploding/failing).
4. All these things work in concert. Change one thing, and you have to check the rest. Hence the eCalc link above. Way easier to do it on the computer than to buy stuff and have it not be what you need.

If this is all still Greek to you, I'd suggest perusing this how-to thread on prop and motor selection. Lots of good instruction in here: http://www.rcgroups.com/forums/showthread.php?t=1136470
Lemme know how it goes,
Josh
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Old Nov 08, 2012, 03:58 PM
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I love electric flying. You drive to the field, plug in and fly. The glow guys (slimers!) drive to the field, fuel the plane, spend an hour screwing around with the motor, fly, unfuel and then try to clean the slime off. At my field, I estimate that the electric guys easily fly twice as much as the glow or gas guys. We now have several 160 size electrics at our field. www.rd-rc.com
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